AAA+ ATPases in Protein Degradation: Structures, Functions and Mechanisms

Area of Science:

• Biochemistry
• Structural Biology
• Molecular Machines

Background:

• AAA+ ATPases are crucial hexameric motor proteins driving cellular processes.
• They utilize ATP binding and hydrolysis for mechanical work, including protein unfolding.
• Advances in cryo-EM enable atomic-level visualization of these complexes.

Purpose of the Study:

• To summarize recent structural and biochemical advances in AAA+ proteases.
• To highlight cryo-EM findings for the 26S proteasome, Cdc48/p97, and FtsH-like proteases.
• To identify conserved structure-function relationships in AAA+ ATPase hexamers.

Main Methods:

• Cryogenic electron microscopy (cryo-EM) for high-resolution structural analysis.
• Biochemical assays to study ATPase activity and substrate processing.
• Comparative structural analysis across different AAA+ proteases.

Main Results:

• Atomic-level 3D structures of AAA+ ATPase complexes during substrate processing were obtained.
• Three conserved structural patterns were identified in AAA+ ATPase hexamers.
• These patterns were observed in the human 26S proteasome, suggesting common mechanisms.

Conclusions:

• Conserved structural motifs underpin AAA+ ATPase function in proteolysis.
• Common dynamic models for mechanochemical coupling and substrate translocation are proposed.
• Cryo-EM has significantly advanced our understanding of AAA+ protease mechanisms.